When running the heat my furnace wont turn off when it hits the temp setting on my digital thermostat. Is it the furnace or the thermostat?
It takes time for the heat to stop after the thermostat hits its set point. The thermostat controls the furnace. The heater fan is controlled by the heat exchanger. so whenever the exchanger is warm the fan blows.
Since the thermostat won't turn it off, how do you turn it off? Do you have to shut the circuit breaker off, unplug the furnace, turn off the gas, or what? That would help narrow down the problem.
It could be either but most likely the thermostat. Also, the thermostat is easier to debug, so start there: 1) Check that your thermostat is set to heat (vs cool). 2) Check that the thermostat is in the “auto” or “on” mode of operation. 3) Check the fan setting. If your thermostat’s fan is set to “on,” then what you think might be your furnace running continuously is actually just your fan running continuously. Switch your thermostat fan to “auto” mode and the fan should go back to being on only when the furnace is actually heating.
